A primary objective in designing and implementing intelligent systems that control and manage cellular communications is to be able to modify radio characteristics of calls in progress so as to maintain, and advantageously improve, the continuing quality of a cellular call. As disclosed in above-referenced, co-pending, commonly assigned U.S. patent application Method and Apparatus for Improved Control Over Cellular Systems, such improved control and management may be enabled by use of a host controller governing the interactive operation of cells in a neighborhood. With reference to this disclosure, it will be appreciated that many of the call management techniques described therein require making modifications, often pretextually, to radio signal conditions of calls in progress. It will be understood that in response to actual or anticipated interference conditions, these pretextual modifications may advantageously trigger various compensating actions such as reverse link power boost, antenna beam change, channel change, handoff, etc.
A problem experienced in the operation of such control and management systems is, however, that the desired modifications often need to be made on a per channel basis. It is well understood that an antenna beam generally transmits or receives a wide spectrum of energy in which multiple calls may be embedded. Modifications to radio characteristics of the beam as a whole will therefore tend to affect all calls whose activity is embedded in the particular antenna beam signal. Further, adaptations of the antenna beam as a whole, and particularly amplification thereof, will tend to alter that beam's interference effect upon other neighboring beams, thereby affecting transmission/reception conditions for radios not even connected to the adapted antenna.
An additional problem exists where it is necessary to have an area in a cell served by a remote antenna, perhaps in a blind spot directly underneath the cell site, or near a bridge or tunnel, or in a mall. In these situations case the coverage is very difficult to be obtained from conventionally placed co-located antennas, and often the remote antenna has to be physically located some distance away. Serving a cell with one or more such remote antennas can create a serious problem in cell site control, in that radio channels must be dedicated to serve that particular area. The control channel nonetheless has to appear as though it is serving a sector in the coverage area. This therefore creates a confusing situation for the cell site controller, which cannot tell whether the antenna it sees is a standard antenna located within the coverage area outdoors, or a remote antenna located within a building or another place where calls must be serviced differently.
Occasionally such remote antenna coverage is impractical or simply not provided in the cellular network. An example of this situation may be inside long tunnels. In such cases, blackout zones appear in the network. Even though the location of these blackout zones is known, and the passing there through by mobile signals can be identified and predicted, it is common for calls passing through blackout zones nonetheless to become disconnected. This is usually either because the pass-through time exceeds a predetermined silence time, typically about 5-10 seconds, after which the system automatically disconnects all calls, or because the land line party assumes a fault and hangs up.
There is, therefore, a need to be able to the modify radio characteristics, and pretextually when necessary, of a particular call signal being broadcast on an antenna on a particular channel, without affecting other call signals embedded in the same antenna signal, so as to enable improved control over call activity, advantageously on a neighborhood basis. There is also a need to be able, when required, to connect radio signals to remote antennas that are independent of and additional to the standard coverage areas, and to be able to manage calls connected thereto seamlessly with the rest of the cell site, including accounting for the particular needs of such non-standard coverage. Such needs may also include preventing an automatic disconnect when a mobile is in a known blackout zone, and alerting the land line party to stand by and not hang up while the mobile party is passing through such a blackout zone.